Field
The present invention relates to a semiconductor device used, for example, for switching of a large current.
Background
JP 2015-130523A discloses an arrangement having, at a position in a drift layer remote from a voltage-withstanding main junction in an insulated gate bipolar transistor (IGBT) or a diode, a field stop layer of the same conduction type as that of the drift layer and having an impurity concentration higher than that in the drift layer. The provision of the field stop structure enables inhibition of a depletion layer extending from the voltage-withstanding main junction at the time of turning off the semiconductor device and, hence, prevention of punch-through.
With respect to a semiconductor device called a power device, there are various requirements for reducing a loss, securing withstand voltage maintenance ability, securing a safe operation region for avoiding breakdown of the semiconductor device during operation, etc. Devices reduced in size and weight have been developed by satisfying such requirements. In recent years, a demand has arisen for electromagnetic compatibility (EMC) in addition to the above-described requirements. A power device that repeats switching of a high voltage and a large current can be an electromagnetic noise generation source. There is a demand for techniques to inhibit the influence of electromagnetic noise from such a noise generation source on other devices by suppressing the electromagnetic noise. One of measures to inhibit the electromagnetic noise is prevention of ringing at the time of turning off the semiconductor device.